First, to update your video card drivers , you must know what card and operating system (Windows XP / Vista / 7 and 32/64 bit)you have. This information is available through your DXDIAG, please to see these steps if you do not know your hardware.

To update your Nvidia graphics card, you must go to the Nvidia site and then perform a search :

Product Type
Product Series
Product Range
Operating System
Language
Once these fields are completed, simply click on “Search” and then download the driver offered. When it is downloaded, it will be necessary to install it and restart your computer.

For example, if a graphics card Nvidia Geforce 9800GT on a Windows XP (32bit) :